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\begin{equation*}\underline{=\frac{\frac{F'(P_2\!<\!P\!<\!P_3)-F'(P_1\!<\!P\!<\!P_2)}{P_1-P_0}-\frac{F'(P_1\!<\!P\!<\!P_2)-F'(P_0\!<\!P\!<\!P_1)}{P_1-P_0}}{P_1-P_0},}\,\!\end{equation*}
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